feat: add Honcho Cloud connection preset

Adds a "choose-type" step to the settings flow so users can pick between
Honcho Cloud (https://api.honcho.dev, API key required) and Self-Hosted
(URL + optional token) when creating a connection. Multi-instance support
already exists in the data layer, so cloud and self-hosted instances can
coexist.

- new HONCHO_CLOUD_URL constant and isCloudInstance helper in config.ts
- SettingsForm accepts a preset prop; cloud variant locks the endpoint
  and enforces an API key
- InstancesManager gains a ConnectionTypeChooser entry point and renders
  a Cloud icon for cloud instances in the list
- unit tests for both preset paths and cloud edit-mode detection

packages/web/src/routes/settings.tsx

@@ -35,7 +35,7 @@ function SettingsPage() {
 					</h1>
 					<p className="text-sm mt-1" style={{ color: "var(--text-3)" }}>
 						{isFirstRun
-							? "Connect to your self-hosted Honcho instance"
+							? "Connect to Honcho Cloud or your self-hosted instance"
 							: "Manage your Honcho connections"}
 					</p>
 				</div>